Voltage regulating system and voltage regulator

ABSTRACT

A voltage regulating system includes a generator, a battery, a warning light, a starting switch, and a voltage regulator. The voltage regulator includes an exciting driver connected to an exciting winding of the generator so as to excite the exciting winding; a voltage built-up/current leakage protection unit connected to a battery and the exciting driver so as to receive a battery voltage and drive the exciting driver for building the output voltage of the generator, while the generator at low speed operation. The voltage regulator further includes an exciting cut-off driver connected to the exciting driver and the voltage built-up/current leakage protection unit so as to cut the exciting driver off in response to the output voltage of the generator built by the voltage built-up/current leakage protection unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a voltage regulating system that isused in a car and used to regulate the output voltage of a generator,while the generator operates at low speed.

2. Description of Related Art

In general, the generator that is used in a car outputs a voltageaccording to the operation speed of the car engine. The output voltageof the generator charges a battery and provides power to all electronicdevices of the car. Moreover, for petrol cars, the output voltage of thegenerator provides the current required to run the car engine.

The car usually has a voltage regulator to regulate the output voltageof the generator so as to avoid unstable output voltage. The voltageregulator regulates the output voltage down, while the output voltage istoo high, and regulates the output voltage up, while the output voltageis too low. Therefore, the voltage regulator can stabilize the outputvoltage of the generator so as to provide stable power to everyelectronic device of the car and to prevent damage of the electronicdevices.

FIG. 1 is a circuit diagram of a prior art voltage regulating system. Asshown in FIG. 1, a voltage regulator 10 of the voltage regulating system1 has three terminals A, F and G, wherein terminal A of the voltageregulator 10 connects to the first output terminal T1 of a generator 12,and connects to the second output terminal T2 of the generator 12 via awarning light 14 and a starting switch 15. Moreover, terminals A and Fof the voltage regulator 10 connect to an exciting winding 122 of thegenerator 12, and terminal G of the voltage regulator 10 connects toground g. The voltage regulating system 1 further includes a battery 13,wherein the positive terminal of the battery 13 connects to the secondoutput terminal T2 of generator 12, and the negative terminal of thebattery 13 connects to ground g.

Please refer to FIG. 1 again. The voltage regulator 10 includes acurrent limit resistor Rb, wherein one terminal of the current limitresistor Rb connects to terminal A of the voltage regulator 10, andanother terminal of the current limit resistor Rb connects to the baseof a Darlington transistor Q. The collector of the Darlington transistorQ connects to terminal F of the voltage regulator 10 and connects toterminal A of voltage regulator 10 via a Freewheeling diode D1, and theemitter of the Darlington transistor Q connects to terminal G of thevoltage regulator 10. Moreover, the voltage regulator 10 furtherincludes a cut-off switch Q2, wherein the cut-off switch Q2 connects thebase and the emitter of Darlington transistor Q. Furthermore, thecontrol terminal of cut-off switch Q2 connects to terminal A of thevoltage regulator 10 via a Zener diode D2.

Please refer to FIG. 1 again. When the starting switch 15 turns on, thebattery 13 supplies the battery voltage to the base of Darlingtontransistor Q via the warning light 14 and the current limit resistor Rbso as to turn on Darlington transistor Q. Moreover, the battery 13outputs an exciting current to the exciting winding 122 of generator 12through the conducting Darlington transistor Q. Then the generator 12starts to build up the output voltage.

The generator 12 transmits the output voltage to cut-off switch Q2 so asto turn on cut-off switch Q2 after the generator 12 has built up theoutput voltage. Moreover, the cut-off switch Q2 that is turned oncouples the base and the emitter of Darlington transistor Q thus cuttingoff Darlington transistor Q. According to the non-conduction ofDarlington transistor Q, the voltage across the exciting winding 122 isgradually reduced through the Freewheeling diode D1. This causes theoutput voltage generated by the first output terminal T1 of thegenerator 12 to drop down, which causes the cut-off switch Q2 to beturned off.

Consequently, the Darlington transistor Q turns on again due to thebattery voltage generated by the battery 13 while cut-off switch Q2 isturned off. The conduction of Darlington transistor Q excites theexciting winding 122 of generator 12 so that the output voltage ofgenerator 12 is raised up again.

The disadvantage of this arrangement is that the functionality ofvoltage regulator 10 depends on the power rating of the warning light14, which must be about 3 W. When warning lights with a power rating of2 W or 1.4 W or high light LEDs are used, the exciting current flowingthrough exciting winding 122 will be too low, and consequently thegenerator 12 will build up the required output voltage only at highspeed of rotation.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a voltageregulator and a voltage regulating system which allows for differentpower ratings of the warning light and allows to build up the outputvoltage of a generator while the generator operates at low speed.

The voltage regulating system of the present invention includes agenerator having an exciting winding and two output terminals; a batteryconnected to one output terminal of the generator and outputting abattery voltage; a warning light connected to another output terminal ofthe generator; a starting switch connected between to the battery andthe warning light; a voltage regulator connected to the generator andthe battery.

The voltage regulator of the present invention connects to a generatorand a battery, wherein the voltage regulator includes an exciting driverand a voltage built-up/current leakage protection unit. The excitingdriver connects to an exciting winding of the generator so as to excitethe exciting winding. The voltage built-up/current leakage protectionunit connects the battery and the exciting driver so as to receive thebattery voltage and drive the exciting driver for building the outputvoltage of the generator, while the generator at low speed operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects and advantages of the present invention will be morereadily understood from the following detailed description when read inconjunction with the appended drawings, in which:

FIG. 1 is a circuit diagram of a prior art voltage regulating system;

FIG. 2 is a circuit diagram of the voltage regulating system accordingto a first embodiment of the present invention;

FIG. 3 is a circuit diagram of the voltage regulating system accordingto a second embodiment of the present invention;

FIG. 4 is a circuit diagram of the voltage regulating system accordingto a third embodiment of the present invention;

FIG. 5 is a circuit diagram of the voltage regulating system accordingto a fourth embodiment of the present invention; and

FIG. 6 is a circuit diagram of the voltage regulating system accordingto a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a circuit diagram of the voltage regulating system accordingto a first embodiment of the present invention. The voltage regulatingsystem 2 is used in a car (not shown), which includes a generator 22having an exciting winding 222 and two output terminals T1, T2; abattery 23 connected to one output terminal T2 of the generator 22; awarning light 24 connected to terminals T1 and T2 of the generator 22; astarting switch 25 connected between the battery 23 and the warninglight 24; a voltage regulator 20 connected to generator 22 and battery23. Moreover, the generator 22 is formed by connecting together analternator 220 and a rectifier 221. Furthermore, the warning light 24 isa LED in this embodiment.

Please refer to FIG. 2 again. The voltage regulator 20 includes anexciting driver 202, an exciting cut-off driver 204 and a voltagebuilt-up/current leakage protection unit 206. The exciting driver 202connects to the exciting winding 222 of the generator 22 so as to excitethe exciting winding 222. The voltage built-up/current leakageprotection unit 206 connects to the battery 23 and the exciting driver202 so as to receive a battery voltage and drive the exciting driver 202for building an output voltage of the generator 22 while the generator22 operates at low speed. The voltage regulator 20 further includes aFreewheeling diode D1, which connects the exciting driver 202 and thevoltage built-up/current leakage protection unit 206, and in parallelconnects the two ends of exciting winding 222.

Please refer to FIG. 2 again. The exciting driver 202 includes a currentlimit resistor Rb having two terminals and a power transistor Q1 havinga base, a collector and an emitter. Moreover, one terminal of thecurrent limit resistor Rb connects to the voltage built-up/currentleakage protection unit 206, and another terminal of the current limitresistor Rb connects to the base of power transistor Q1. The collectorof power transistor Q1 connects to exciting winding 222, and the emitterof power transistor Q1 connects to ground g. Furthermore, the powertransistor Q1 is a Darlington transistor in this embodiment.

The exciting cut-off driver 204 connects to exciting driver 202 andvoltage built-up/current leakage protection unit 206. When the outputvoltage of generator 22 is built, the output voltage of generator 22drives the exciting cut-off driver 204 via the voltage built-up/currentleakage protection unit 206 to cut off exciting driver 202. The excitingcut-off driver 204 is formed by connecting in series a Zener diode D2and a cut-off switch Q2.

Please refer to FIG. 2 again. The voltage built-up/current leakageprotection unit 206 includes a first transistor Q3, a first resistor R1,a second transistor Q4 and a second resistor R2. Moreover, the collectorof the first transistor Q3 connects to the exciting cut-off driver 204,and the emitter of first transistor Q3 connects to the battery 23. Thefirst resistor R1 connects the base and the emitter of first transistorQ3. The base of the second transistor Q4 receives the battery voltage,the emitter of second transistor Q4 connects to ground g, and thecollector of second transistor Q4 connects to the base of the firsttransistor Q3 via the second resistor R2.

Please refer to FIG. 2 again. The voltage regulator 20 has fourterminals B+, A, F and G, wherein the terminal A of the voltageregulator 20 connects to the first output terminal T1 of the generator22, and connects to the second output terminal T2 of the generator 22via the warning light 24 and starting switch 25. Moreover, terminals Aand F of the voltage regulator 20 connect the two ends of excitingwinding 222 of generator 22, the terminal G of the voltage regulator 20connects to ground g, and the terminal B+ of the voltage regulator 20connects to the battery 23. Furthermore, the positive terminal ofbattery 23 connects to the second terminal T2 of generator 22, and thenegative terminal of the battery 23 connects to ground g.

Please refer to FIG. 2 again. When the starting switch 25 turns on, thebattery 23 supplies battery voltage to the base of second transistor Q4of the voltage built-up/current leakage protection unit 206 via thewarning light 24 to turn on the second transistor Q4. The secondtransistor Q4 that is turned on couples the base of the first transistorQ3 to ground g via the second resistor R2 so as to put the voltage levelof the base of the first transistor Q3 to zero, thus turning on thefirst transistor Q3. The battery 23 further supplies battery voltage tothe emitter of first transistor Q3.

The voltage of battery 23 is transmitted to the base of the Darlingtontransistor Q1 via the conduction of the first transistor Q3 and thecurrent limit resistor Rb so as to turn on the Darlington transistor Q1.Moreover, the battery 23 outputs an exciting current to the excitingwinding 222 of generator 22 through the conduction of Darlingtontransistor Q1. Then the generator 22 starts to build up the outputvoltage.

According to the above, the battery voltage bypasses the warning light24 but instead passes through the voltage built-up/current leakageprotection unit 206 to the exciting driver 202 so as to turn on theDarlington transistor Q1 by a driving current IB. Moreover, theconduction of the Darlington transistor Q1 has a small collector-emittervoltage VCE, which can generate a large exciting current. The largerexciting current results in the build-up of the output voltage ofgenerator 22 while the generator 22 operates at low speed.

The voltage built-up/current leakage protection unit 206 of the voltageregulator 20 can turn on the Darlington transistor Q1 of the excitingdriver 202 fully. Thus, the battery 23 can supply a large excitingcurrent to the exciting winding 222 via the warning light 24, buildingup the output voltage of generator 22 while the generator 22 operates atlow speed. Therefore, the voltage regulating system 2 with the voltageregulator 20 is suitable for use with various warning lights 24 havingpower ratings such as 3 W, 2 W, 1.4 W, or with a high light LEDconnected in parallel to a resistor.

The generator 22 transmits the output voltage to the exciting cut-offdriver 204 to turn on the cut-off switch Q2 of exciting cut-off driver204 after the generator 22 has built up the output voltage. The turnedon cut-off switch Q2 couples the base and the emitter of Darlingtontransistor Q1 to cut off Darlington transistor Q1. According to thenon-conduction of Darlington transistor Q1, the voltage across theexciting winding 122 is gradually reduced through the Freewheeling diodeD1. At this time, the output voltage of the generator 22 drops down andthus turns off the cut-off switch Q2. Thus, the Darlington transistor Q1turns on again according to the driving current IB generated from thebattery 23 while cut-off switch Q2 is turned off. The conduction ofDarlington transistor Q1 excites the exciting winding 222 of thegenerator 22 so as to raise up again the output voltage of generator 22.

Please refer to FIG. 2 again. The voltage built-up/current leakageprotection unit 206 is turned off while the car engine is stoppedbecause the voltage at emitter and base of first transistor Q3 is equal.This prevents a leakage current through current limit resistor Rb andavoids power consumption from battery 23.

Reference is made to FIG. 3 and FIG. 2. In the second embodiment,components identical to those used in the first embodiment are labelledwith the same symbols. The circuit actions and achieved effects of thevoltage regulator 20 a of the second embodiment are the same as those ofthe voltage regulator 20 of the first embodiment. The second embodimentdiffers from the first embodiment only in that the exciting cut-offdriver 204 a of the second embodiment further includes an auxiliaryswitch Q5 for enhancing the operating speed of exciting cut-off driver204 a.

Reference is made to FIG. 4 and FIG. 2. In the third embodiment,components identical to those used in the first embodiment are labelledwith the same symbols. The circuit actions and achieved effects of thevoltage regulator 20 b of the third embodiment are the same as those ofthe voltage regulator 20 of the first embodiment. The third embodimentdiffers from the first embodiment only in that the general powertransistor Q1′ of the third embodiment replaces the Darlingtontransistor Q1 of the first embodiment.

Reference is made to FIG. 5 and FIG. 2. In the fourth embodiment,components identical to those used in the first embodiment are labelledwith the same symbols. The circuit actions and achieved effects of thevoltage regulator 20 b of the fourth embodiment are the same as those ofthe voltage regulator 20 of the first embodiment. The fourth embodimentdiffers from the first embodiment in that the exciting cut-off driver204 c of the fourth embodiment further includes an auxiliary switch Q5for enhancing the operative speed of the exciting cut-off driver 204 c.Moreover, the general power transistor Q1′ of the fourth embodimentreplaces the Darlington transistor Q1 of the first embodiment.

Reference is made to FIG. 6 and FIG. 2. In the fifth embodiment,components identical to those used in the first embodiment are labelledwith the same symbols. The circuit actions and achieved effects of thevoltage regulator 20 d of the fifth embodiment are the same as those ofthe voltage regulator 20 of the first embodiment. The fifth embodimentdiffers from the first embodiment only in that the voltagebuilt-up/current leakage protection unit 206 is omitted in the fifthembodiment. Thus, in the fifth embodiment, the exciting driver 202 isconnected to the battery 23 directly via terminal B+ and the currentlimit resistor Rb.

To Sum up, the voltage regulator of the present invention includes anexciting driver, an exciting cut-off driver and a voltagebuilt-up/current leakage protection unit. The exciting driver connectsto the exciting winding of the generator so as to excite the excitingwinding. Moreover, the voltage built-up/current leakage protection unitconnects to the battery and the exciting driver so as to receive thebattery voltage and drive the exciting driver for building up the outputvoltage of the generator while the generator operates at low speed.Furthermore, the exciting cut-off driver connects to the exciting driverand the voltage built-up/current leakage protection unit so as to cutthe exciting driver off in response to the output voltage of thegenerator built by the voltage built-up/current leakage protection unit.

Therefore, the voltage regulator of the present invention has theadvantages of allowing the usage of warning lights of different powerratings and enabling the generator to build up the output voltage at lowoperating speed.

Although the present invention has been described with reference to thepreferred embodiment, it shall be understood that the invention is notlimited to the details thereof. Various substitutions and modificationshave been suggested in the foregoing description, and others will occurto those of ordinary skill in the art. Therefore, all such substitutionsand modifications are intended to be embraced within the scope of theinvention as defined in the appended claims.

1. A voltage regulator connected to a generator and a battery, comprising: an exciting driver connected to an exciting winding of the generator for exciting the exciting winding; and a voltage built-up/current leakage protection unit connected to the battery and the exciting driver for receiving a battery voltage and driving the exciting driver so as to built an output voltage of the generator while the generator operates at low speed.
 2. The voltage regulator as claimed in claim 1, further comprising a freewheeling diodeconnected to the exciting winding in parallel.
 3. The voltage regulator as claimed in claim 1, wherein the exciting driver comprises: a current limit resistor having two ends, wherein one end of the current limit resistor connects to the voltage built-up/current leakage protection unit; and a power transistor having a base, a collector and an emitter, wherein the base of the power transistor connects to the other end of the current limit resistor, the collector of the power transistor connects to the exciting winding, and the emitter of the power transistor connects to a ground.
 4. The voltage regulator as claimed in claim 3, wherein the power transistor is a Darlington transistor.
 5. The voltage regulator as claimed in claim 2, further comprising an exciting cut-off driver, wherein the exciting cut-off driver connects to the exciting driver and the voltage built-up/current leakage protection unit for cutting the exciting driver off in response to the output voltage of the generator built by the voltage built-up/current leakage protection unit.
 6. The voltage regulator as claimed in claim 5, wherein the voltage built-up/current leakage protection unit comprises: a first transistor having a base, a collector and an emitter, wherein the collector of the first transistor connects to the exciting cut-off driver, the emitter of the first transistor connects to the battery; a first resistor connecting the base of the first transistor and the emitter of the first transistor; a second transistor having a base, a collector and an emitter, wherein the base of the second transistor receives the battery voltage, the emitter of the second transistor connects to the ground; and a second resistor connecting the base of the first transistor and the collector of the second transistor.
 7. The voltage regulator as claimed in claim 1, wherein the generator is composed of an alternator and a rectifier.
 8. A voltage regulating system, comprising: a generator having an exciting winding and two output terminals; a battery connected to one output terminal of the generator and outputting a battery voltage; a warning light connected between the two output terminals of the generator; a starting switch connected between to the battery and the warning light; a voltage regulator connected to the generator and the battery, wherein the voltage regulator comprises: an exciting driver connected to the exciting winding of the generator for exciting the exciting winding; and a voltage built-up/current leakage protection unit connected to the battery and the exciting driver for receiving the battery voltage and driving the exciting driver so as to build an output voltage of the generator while the generator operates at low speed.
 9. The voltage regulating system as claimed in claim 8, further comprising a freewheeling diode, wherein the freewheeling diode is connected to the exciting winding in parallel.
 10. The voltage regulating system as claimed in claim 8, wherein the exciting driver comprises: a current limit resistor, wherein one terminal of the current limit resistor connects to the voltage built-up/current leakage protection unit; and a power transistor having a base, a collector and an emitter, wherein the base of the power transistor connects to another terminal of the current limit resistor, the collector of the power transistor connects to the exciting winding, the emitter of the power transistor connects to a ground.
 11. The voltage regulating system as claimed in claim 10, wherein the power transistor is a Darlington transistor.
 12. The voltage regulating system as claimed in claim 9, further comprising an exciting cut-off driver, wherein the exciting cut-off driver connects to the exciting driver and the voltage built-up/current leakage protection unit for cutting the exciting driver off response to the output voltage of the generator built by the voltage built-up/current leakage protection unit.
 13. The voltage regulating system as claimed in claim 12, wherein the voltage built-up/current leakage protection unit comprises: a first transistor having a base, a collector and an emitter, wherein the collector of the first transistor connects to the exciting cut-off driver, the emitter of the first transistor connects to the battery; a first resistor connecting the base of the first transistor and the emitter of the first transistor; a second transistor having a base, a collector and an emitter, wherein the base of the second transistor receives the battery voltage, the emitter of the second transistor connects to ground; and a second resistor connected between to the base of the first transistor and the collector of the second transistor.
 14. The voltage regulating system as claimed in claim 8, wherein the warning light is an LED.
 15. The voltage regulating system as claimed in claim 8, wherein the generator is composed of an alternator and a rectifier.
 16. A voltage regulator connected to a generator and a battery, comprising: an exciting driver connected to an exciting winding of the generator for exciting the exciting winding so as to build an output voltage of the generator while the generator operates at low speed, wherein the exciting driver comprises: a current limit resistor, wherein one terminal of the current limit resistor connects to the battery for receiving a battery voltage; and a power transistor having a base, a collector and an emitter, wherein the base of the power transistor connects to another one terminal of the current limit resistor, the collector of the power transistor connects to the exciting winding, the emitter of the power transistor connects to a ground.
 17. The voltage regulator as claimed in claim 16, further comprising a freewheeling diode, wherein the freewheeling diode is connected to the exciting winding in parallel.
 18. The voltage regulator as claimed in claim 16, wherein the power transistor is a Darlington transistor.
 19. The voltage regulator as claimed in claim 16, further comprising an exciting cut-off driver, wherein the exciting cut-off driver connects to the exciting driver and the battery for cutting the exciting driver off response to the output voltage of the generator.
 20. The voltage regulator as claimed in claim 16, wherein the generator is composed of an alternator and a rectifier. 